Building a Scroungemaster

Sig Skyray 35

Building a Scroungemaster

Welcome to my first Building Guide. When I first got into flying Control Line model airplanes, one of the things I noticed is that some of the kits available have kind of confusing or sparse instructions, even kits that are supposedly designed for beginners. In these cases it might be useful to have a detailed building guide to help "flesh out" the instructions that came with the kit. I don't really feel like that kind of info belongs in a product review, so that is one of the reasons for this section. The other reason is that I want to have a place to publish my ideas on kitbashing or scratch building model airplanes. The first project, which I'm just getting started on, combines a Sterling S1-A Ringmaster fuselage with a modified Shark 402 wing. I'm going to call the resulting model the Scroungemaster.

Why would anyone want to do this?

Well, everyone has their reasons, and some of the reasons must be good enough to build on. Modified Ringmasters are hardly anything new. The Twistmaster combines a Rinmaster fuselage and tail with the wing from a Sig Twister, while the Tutormaster combines a Ringmaster wing with a Tutor fuselage and tail feathers. In the case of my Scroungemaster, I really like the look of the Ringmaster, and I have a fuselage and tail surfaces that I cut from a friend's templates. However, the kit ribs were unusable to me since the S1-A uses a diamond shaped piece of balsa (which is impossible to find) for the leading edge. Since I didn't really want to design my own wing, I decided to try to find something that would work, and the Shark 402 rib profile looked like it would fit pretty well with the Ringmaster fuselage.

Design Thoughts

One of my friends asked me why I didn't just buy a set of S-1 Ringmaster ribs from Eric Rule at RSM Distribution. The S-1 has a thinner wing than I wanted, and the wing construction is something I don't want to tackle until I have a little more building experience. (I have RSM's S-1 kit BTW and it is really nice. I'll do a product review in the spring when I build it). I also felt a little more wing area would help the plane fly at the slower speeds I want while I'm learning to fly. While building a Brodak Shark 402, I noticed it had a pretty nice airfoil. Then I found out they sell laser cut rib sets for only $12.00 - BANG - I know what to use for the Scroungemaster wing!

Of course, the wing won't be "perfect." The tip cord is larger than the stock Ringmaster, so to get a decent looking taper on the trailing edge I had to make the tip cord wider as well which has the effect of making the already too short tail even shorter. I'm going to offset this by moving the wing forward, which is possible because I'm going to power the thing with an FP-20 which can use a smaller tank that doesn't need as much room in front of the wing. Tail surfaces will stay the same but elevator throw will be limited to 20 degrees, based on tips from people way more knowledgable about such things than I am. To maintain the vbintage look that I adore so much, I'm going to use a plywood elevator horn, wire landing gear (am I the only one who thinks sheet aluminum landing gears are ugly?) and the paint scheme from the original Ringmaster magazine ad.

Results

Will I end up with a good flying airplane? Time will tell... I'm starting with a too short tail and too large elevator, factors I hope I can compensate for with trimming and srtuctural changes. On the plus side, I'll have a bigger, thicker wing which should turn better at lower speeds (especially at the altitude in Reno) and I'm running an engine setup that reportedly has much better power delivery than the Fox .35's of yesteryear. Regardless of how it flies, I know it will be a fun build and I hope to learn a lot. Check back in about a month to see how it's coming along.

Posted December 7, 2006

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